From owner-freebsd-performance@FreeBSD.ORG Fri Dec 16 15:00:46 2005 Return-Path: X-Original-To: freebsd-performance@freebsd.org Delivered-To: freebsd-performance@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id A585516A41F for ; Fri, 16 Dec 2005 15:00:46 +0000 (GMT) (envelope-from mark@hubcapconsulting.com) Received: from biodiesel.gaiahost.coop (biodiesel.gaiahost.coop [64.95.78.120]) by mx1.FreeBSD.org (Postfix) with ESMTP id C9CC843D5F for ; Fri, 16 Dec 2005 15:00:42 +0000 (GMT) (envelope-from mark@hubcapconsulting.com) Received: from localhost (host-64-65-195-19.spr.choiceone.net [::ffff:64.65.195.19]) (AUTH: LOGIN mark@hubcapconsulting.com) by biodiesel.gaiahost.coop with esmtp; Fri, 16 Dec 2005 10:00:39 -0500 id 000F0045.43A2D698.00003754 Received: by localhost (sSMTP sendmail emulation); Fri, 16 Dec 2005 10:00:57 -0500 Date: Fri, 16 Dec 2005 10:00:57 -0500 From: Mark Bucciarelli To: freebsd-performance@freebsd.org Message-ID: <20051216150057.GN592@rabbit> References: <20051213205244.GQ2188@rabbit> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20051213205244.GQ2188@rabbit> User-Agent: Mutt/1.4.2.1i X-Mailman-Approved-At: Fri, 16 Dec 2005 15:11:13 +0000 Subject: Re: [LONG] vmstat: What I/O is blocked and how to fix it? X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 16 Dec 2005 15:00:46 -0000 On Tue, Dec 13, 2005 at 03:52:44PM -0500, Mark Bucciarelli wrote: > On two occasions recently, vmstat has showed me that a > number of processes are blocked due to I/O. At the same > time, the number of disk transactions per second reported is > a small fraction of the disk's capability. I did a lot of reading to try and understand what was happening to this heavily loaded box. The most helpful resources I found were posts by Andrew Kinney [1][2], Terry Lambert [3][4], and Daniel Lang [5], as well as the VM design elements doc written by Mathew Dillon [6]. I figure the kernel did not have enough memory to operate efficiently. I set KDA_PAGES = 512 and the new kernel didn't show any blocked processes for the spamd-setup test. :) A first question: There were notes that the kernel auto-sizes things like memory for files and other things based on the amount of memory available. In this context, does "memory available" = RAM + swap? So now I should monitor things. I think I know how to watch network buffers and paging, are there any other stats I should watch? - network buffers (netstat -m) - vm page pointers (vmstat -z, PV_ENTRY "free" + "used" >= 90% of "limit") - anything else? Any other recommended reading? Thanks for any pointers. m [1] http://lists.freebsd.org/pipermail/freebsd-hackers/2004-February/005528.html [2] http://unix.derkeiler.com/Mailing-Lists/FreeBSD/hackers/2003-12/0221.html [3] http://lists.freebsd.org/pipermail/freebsd-current/2003-June/005691.html [4] http://unix.derkeiler.com/Mailing-Lists/FreeBSD/hackers/2003-12/0229.html [5] http://freebsd.hanirc.org/holyboard/holyboard.cgi?db=hackers&mode=view&now=55&no=26202&jd=-1 [6] http://ezine.daemonnews.org/200001/freebsd_vm.html